This is for IGCSE Double Award Biology (EDEXCEL), tailored to the 2009 specification. If you spot any mistakes, please let me know, thank you! I hope you find this useful!
This blog is no longer updated as I've finished IGCSEs in 2012. I may sometimes reply to questions if you comment or email me, but not guaranteed. I hope what I had time to post back during IGCSEs helps anyway!! :)

Pages

Search This Blog

IB HL Bio Notes For Sale

Hi! If you are interested in buying scanned PDF copies of my handwritten HL Bio notes, please find the links below. Previews are available! Clicking on the links simple redirect you to a description of the notes + a preview. :)

Wednesday, 9 May 2012

Respiration

2.33
recall that the process of respiration releases energy in living organisms

Just recall
this. Energy is locked up in food molecules such as glucose. Living organisms release energy by breaking these molecules down. Without respiration, you wouldn’t have energy to do all your physical
activities and survive.

Plants and most animals, including humans,
respire aerobically. These complex organisms need a lot of energy to survive.
Some examples of energy-consuming processes in organisms are:

The synthesis of proteins from amino acids

Cell division

Muscular contractions such as heartbeats and
respiratory movements

Active transport in the absorption of food
substances by the small intestine

Transmission of nerve impulses or messages

2.34
describe the differences between aerobic and anaerobic respiration

Aerobic respiration is with oxygen, anaerobic
respiration is without. Basically, your muscle cells can respire anaerobically
for short periods of time when there is a shortage of oxygen.

Aerobic respiration is actually a multi-step reaction that is catalysed by enzymes in the mitochondria.

And aerobic respiration releases more energy,
but the good thing with anaerobic respiration is that it’s almost instant, it’s
quick-which is why events such as a 100m sprint
which requires a quick burst of energy is anaerobic.

But anaerobic respiration leads to the
production of lactic acid-a poison, which builds up in your muscles. The lactic
acid concentrations build up slowly in the muscles and may eventually become
high enough to cause fatigue, muscular pains and cramps to stop you from
continuing.

This is why you continue to breathe hard after anaerobic
exercise for a while, as you are repaying your oxygen debt, which is the oxygen required to oxidize and convert
the harmful lactic acid into harmless products like carbon dioxide and water.

2.35
recall the word equation and the balanced chemical symbol equation for aerobic
respiration in living organisms

Glucose + oxygen à carbon dioxide + water + energy
(ATP)

My class likes to use ‘ATP’ in place of energy,
and it stands for adenosine triphosphate. It's like the 'currency' of energy. I'll let this link do the explaining of what it is:

http://wiki.answers.com/Q/What_is_ATP
The explanation in the link may be confusing, as we don't need that kind of depth yet. In very basic terms, ATP is like small packets of energy. They store energy temporarily and provide energy for all the reactions taking place in the cell.

C6H12O6
+ 6O2à 6CO2
+ 6H2O + ATP

2.36
recall the word equation for anaerobic respiration in plants and in animals

Glucose à lactic acid + ATP (smaller
amount!)

C6H12O6
à 2C3H6O3
+ ATP

The small amount of energy released in
anaerobic respiration, together with that produced in aerobic respiration, is
sufficient to keep the muscles contracting.

Keep in mind that this equation is different
for alcoholic fermentation where yeast respires anaerobically. This is used in
the production of bread to make bread rise, as the carbon dioxide produced
raises the bread.

Glucose à ethanol + carbon dioxide + small amount of energy

Note that the glucose molecule is only
partially broken down in anaerobic respiration. The ethanol produced still
contains much energy, hence explaining why only a small amount of energy is set
free in anaerobic respiration.

As you can see, anaerobic respiration and removing lactic acid is much more complex than what I've described, but you don't need to concern yourself with glycolysis for now. Just know the equations I've stated above and all the general stuff. :)

Community Service

About Me

Hi I'm Michelle. I've finished IGCSEs and the IB but I hope these blogs help people with their IGCSEs anyway!! :)

Note: That's why these blogs are no longer updated, what's there is all I had time for back then so I'm sorry that they're not fully complete with the whole syllabus and all. Hope what's there helps anyway.. :)

I do actually have more notes than is posted, and these can be purchased by buying my IGCSE Notes sets.

Blog Archive

Hi!

Note: This blog will no longer be updated, but I will read emails.

So, I've finished IGCSEs but I'm leaving my blogs open in hopes that they help people. It would be great if you can tick a box at the bottom of each post to show me what you think, and please feel free to leave comments! A Google+1 below would be awesome too. Thank you so much, hope they help. :)

Btw, I did take information out of textbooks. But I've reworded what I can.